Radio receiving system



'fmr 2%, W36 H. J. NlcHoiL lx-:T M. www? RADIO RECEIVING SYSTEM Filed sept. 21, 1952 m d ma 5r www w WHL h mi@ VMRAW WTE www m m Patented Apr. 28, 1936 UNITED STATES PATNT QFFIQE RADIO RECEIVING SYSTEM Application September 21, 1932, Serial No. 634,138

1 Claim.

This invention relates to a radio receiving system and is particularly adapted to a remotely controlled radio receiving device.

An object of this invention is to provide a selective unit for use with a radio wave translating device that may be iiexibly attached to said de- Vice and control the device in accordance with the desires of an operator.

Another object of this invention is to provide a control unit for a radio receiver Which receives its operating potentials and currents from the radio receiver with which it is used.

Another object of this invention is to provide a means for controlling the volume output of a radio receiving system by controlling the voltage of the signal energy between the signal frequency selecting unit and the amplifying unit.

Another object of this invention is to provide an improved means for mixing the signal energy with locally generated oscillations.

Another object of this invention is to provide a means for supplying the filament or cathode heating current for one or more tubes of a radio circuit by utilizing the normal operating current of one or more other tubes.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawing:

'I'he single ligure discloses a circuit of a remote controlled unit for a radio receiver, and indicates r essential elements of the receiver or amplifier to which the control unit is connected.

With particular reference to the drawing, a primary inductance I) is connected in series with an antenna I and a ground 2. 'Ihe primary inductance II) is magnetically coupled to a secondary inductance I4 to form the coupling unit I2, and the grounded end of the primary inductance IB is connected to one end of the secondary inductance I4. The other end of the secondary .inductance I4 is connected to an input or control electrode I8 of a thermionic detector tube 20. A variable condenser I6 is connected to the ends of the secondary inductance I4 to form a `tunable lresonant circuit 25.

The detector tube 20 has, beside the input or control electrode I8, a lament or cathode element 22, a screen grid 24 and an anode or output electrode 26 therein. The screen grid 24 is connected to a tap 28 on a resistor 30. The extremities of the resistor 30 are connected to ground at 32 Vand Lto a lead 34. The lead 34 Yis (Cl. Z50- 20) connected to a convenient point of a radio device from which a positive potential may be obtained of suflicient magnitude for the elements of the tubes to which it is connected. The anode or output electrode 26 is connected to the lead 34 through inductances 36 and 38 which are connected in series.

A condenser 4t connected between the screen grid 24 and one side of the filament 22, and a condenser 42 connected between the lead 3i and the same side of the filament circuit, form bypass circuits for any high frequency currents from the screen grid 24 and anode 26 respectively. The same side of the iilament 22 that is connected to the condenser 4i), is connected through a choke iliand a resistance It to ground at 2. A condenser 48 has one side connected to a point intermediate the inductances 3@ and 38, and its other side connected to a resistor 50, which has a Variable tap 52 connected to a lead 5G of a cable, and an end connected to ground at 54. The same side of the filament 22 that connects to the condenser ii and the choke 44 is connected to one side of a condenser 58, that is in turn connected to ground at tit through an inductance 62. The other side of the filament 22 is connected to one side of a filament 6ft of a thermionic oscillator tube 6G.

The thermionic oscillator tube 66 has an anode 68 connected through an inductance 'IEI and a resistor l2 to the tap 2B on the resistor 30. A control electrode lli of the thermionic tube 6B is connected through a resistance it to that side of the iilament t4 that connects to the filament 22. The control electrode 'i4 is also connected to one end of an inductance i8. Condensers 30 and 82 are connected in series, and one end of the series combination is connected to an end of the inductance is, while the other end of the series combination is connected to a point intermediate the inductance it and the resistor l2. A variable condenser 84 is connected across the inductance I8 and the condenser t@ to form a tunable resonant circuit 86. The common connection of the condensers l and 82 is grounded at 88. One side of the filament 64 is connected to a lead 96 of a cable.

A condenser 94 and an inductance 92 are connected in series, and one end of the series combination is connected to the lead 56 of a cable While the other end of the combination is connected to an inductance 90. The inductance 90 is magnetically coupled to an inductance 98,7and has one of its ends connected to that inductance to form a coupling unit or intermediate frequency transformer |66. The common connection between the inductances and 98 is grounded at |04. The condenser |62 is connected across the inductance 98 to form a resonant circuit |66. The high potential end of the inductance 98 is connected to a control electrode |08 of a thermionic tube ||6. A cathode II2 of the thermionic tube Ill) is connected to ground at |04 through a resistor |I4. The condenser I I6 connected across the resistor I I4 forms a bypass circuit for high frequency currents from the cathode ||2. An anode or output electrode ||8 of the thermionic tube ||0 is connected to a lead |26 through which it may be connected to the input of succeeding similar stages, or of a detector.

A primary inductance |26 of a transformer |25 having leads |22 and |24 adapted for connection to the output of a detector, is magnetically coupled to secondary inductances |28 and |30. The inductance |36 is connected to the inductance |28 and forms a part of the complete secondary, and the connection between the inductances provides a mid-tap to which an end of a resistor |32 is connected. The other end of the resistor |32 is connected to a point intermediate choke |34 and resistor |36 which are connected in series and are in series with the lead 66. The extremities of the secondary formed by the series combination of the inductances |28 and |36 are connected to control electrodes |38 and |46 of the thermionic tubes |42 and |44 respectively. Filaments |46 and |48 of the thermionic tubes |42 and |44 respectively, are connected in parallel, and an impedance |56 having a mid-tap |52 is connected across that parallel combination. An end of the resistor I 36 is connected to the mid-tap |52 of the irnpedance |56. Anodes or output electrodes |54 and |56 of the thermionic tubes |42 and |44 are provided with leads |58 and |66 respectively, for connection to an output transformer or other suitable output circuit.

When signals are picked up by the antenna I, they are applied to the input or control electrode I8 through the coupling device I2. The tuning of the resonant circuit 25 by the variable condenser |6 serves as a selective means to select the desired incoming signals. At the same time the incoming signals are being applied to the control electrode I8 of the detector tube 20, locally generated oscillations are picked up by the inductance 62 by virtue of its magnetic coupling with the inductance '18, and are applied to the i'ilament or cathode element 22 of the detector tube 26 through the condenser 58. The tuning of the variable condenser 84 determines the resonant frequency of the resonant circuit 86 and the frequency of oscillation of the oscillator tube 66. By applying the incoming signals to the control electrode I8 of the tube 26 and the locally generated oscillation to the filament 22 of that tube, the signals are mixed with the locally generated oscillation in that tube. The mixed oscillating energy is then applied to the anode or output electrode 26, and thence to the output circuit formed by the inductances 36 and 38, the condenser 48, the resistor 56 and its variable tap 52, and the lead 56.

The difference in frequency between that of the signals applied to the control electrode I8 of the detector 26 and that of the oscillator 66 determines the frequency of the oscillating energy applied to the output electrode 26. Hence, if the condensers I6 and 84 are properly aligned and tuned in unison, the frequency of the output energy may be kept constant regardless of the frequency of the signal being received.

The biasing potential for the detector tube 26 is applied between the control electrode I8 and lament 22 by virtue of the D. C. potential drop across the choke 44 and resistor 46. The choke 44 has a high reactance to high frequencies and fairly low D. C. resistance so that it tends to prevent the oscillating energy applied to the filament from being by-passed to ground at 2 through the resistor 46. The condenser 58 is large enough to permit the oscillating energy from the oscillation generator to be applied to the iilament 22, but prevents the biasing potential between the lament 22 and control electrode |8 from being short circuited through the inductance 62.

The resistor '|6 connected between the control electrode 'I4 and the lament 64 of the oscillator i."

tube 66 forms a grid leak. The inductance i6 connected to the anode 68 and in series with that anode and its source of potential, and magnetically coupled with the inductance 78, provides an inductive feed-back to cause the oscillator tube 66 to oscillate. The resistor 36 connected between the lead 34 and ground at 32, and having a tap 28 serves as a voltage divider, so that the voltage applied to the screen grid 24 of the detector 2D is substantially that of the tap 28, 5

and a voltage applied to the anode l68 is equal to that of the tap 28 minus the voltage drop across the resistor I2 and the inductance 76.

The resistor 56 connected to ground at 54 and to the output circuit intermediate the induc- I'- tances 36 and 38 through the condenser 48, and having a variable tap 52 connected to the lead 56 serves as a variable voltage divider to determine the voltage applied to the input of the amplifying stages. The condenser 48 permits the oscillating output voltage to pass, but isolates the D. C. potential of the anode 26 from ground at 54 and also prevents that potential from being applied to the amplifier. The voltage thus predetermined by the portion of the resistor 56 between ground at 54 and the variable tap 52 is applied to the primary inductance 60 through the condenser 94 and inductance 92, which condenser and inductance serve to tune the lead 56 to be most eiicient at the frequency of the oscillating energy from the detector 26. The secondary resonant circuit |66 is tuned to resonance at the frequency of the oscillating energy applied thereto so that a maximum voltage is applied to the tube I l0 between the control electrode |68 and cathode I I2. The output energy of the tube IIIJ from the anode ||8 may be applied through the lead |26 to other similar amplifying stages, or to a. detector. The biasing potential is applied between the control electrode |68 and the cathode ||2 by virtue of the D. C. potential drop across the resistor |I4.

After the signals have been amplified and detected they are applied to an audio frequency amplifier through the leads |22 and |24 and the primary inductance |26. The voltage induced into the secondary formed by the inductances |28 and |36 due to the magnetic coupling of the inductance |26, is applied to the control electrodes |38 and |46 of the thermionic tubes |42 and |44. F

|46. The biasing potential is applied to the control electrodes through the midtap formed by the connection of the inductances |28 and |30, and through the resistor |32 to permit the signal potential to swing the control electrode potentials either side of the biasing potential, and in a manner such that the signal potentials applied to the control electrodes |38 and |40 will be 180 out of phase. The amplified output signal energy from the anodes |56 and |54 may then be applied to an output transformer or other suitable output circuit through leads |58 and |60 to be reproduced.

The lead 96 connected to the series combination of the filament 64 of the oscillator tube 66 and the lament 22 of the detector tube 20, and to a point intermediate the resistor |32 and the resistor |36 through the choke |34, provides a path through which the anode current of the tubes |42 and |44 will flow to heat the filaments 64 and 22. The anodes |54 and |56 are kept at a positive potential by connecting them, through a choke to the source B. As is well known to those skilled in the art, the direct current blocking condensers are inserted in leads |58 and |56 to the audio output circuit. The circuit may now be traced as follows: From +B to anodes |54, |56 to cathodes |46, |38, choke |50, resistor |36, choke |34, lead 96, cathodes 64, 22, choke 44, resistor 46, ground 2, ground 32, resistor 30 and lead 34. The choke |34 has a high reactance and low resistance, and by virtue of those characteristics permits the direct component of the anode current to ow therethrough without appreciable impedance, but tends to resist the flow of thealternating component of the anode current through the filaments 22 and 64.

The intermediate stage or stages such as that formed by the tube I l0 and the coupling device |00 may be especially constructed stages, or may be the radio frequency stages of a conventional tuned radio frequency receiver xedly tuned to a predetermined frequency, or may be the radio frequency or intermediate frequency stages of a conventional superheterodyne receiver. The audio frequency stage or stages may be those used with anyone of the previously mentioned forms of amplifiers. Then, the lead 34 may be connected to a suitable point on any of the above mentioned amplifiers from which a satisfactory anode or B potential may be obtained.

The features of this invention are particularly applicable to the type of receiving system disclosed, but might be applied to any type of radio or amplifying device and still come within the scope of the present invention.

While the form of embodiment of the present invention as herein disclosed, constitutes a p-referred form, it is to be understood that other forms might be adopted, all coming within the scope of the claim which follows.

What is claimed is as follows:

In a radio circuit the combination including an audioamplifier provided with at least one electronic tube having an anode, a cathode and a control electrode, a frequency changer circuit including an electronic tube provided with an anode, a cathode and a control electrode and an oscilla.- tion generator circuit including an electronic tube provided with an anode, a cathode and a control electrode, a connection between the anode and cathode of the first mentioned tube including a source of plate current, a resistor, an inductance coil, the cathode energizing circuits of both said second named tubes and a choke coil all in series, an input circuit for the frequency changer including means for biasing the grid of the tube comprising a connection from the grid electrode of the electronic tube thereof to the cathode thereof including said resistor and inductance coil in series, means for impressing the output of the oscillation generator across said inductance coil and resistor, a source of high frequency energy coupled to the input of the frequency changer circuit, said inductance coil being proportioned with respect to the other elements of the circuit so as to prevent the energy impressed across the inductance coil and resistor from being ley-passed by said resistor, said resistor having a comparatively low resistance value.

HARRY J. NICHOLS. HENRY C. FORBES. WALTER S. HARMON. HOMER J. LOF'I'IS. 

